1. Field of the Invention
The present invention relates to a discharge lamp lighting apparatus which is desired to be thin in a depth direction, such as a headlight of an automobile.
2. Description of the Related Art
Recently, a discharge lamp having high luminance has been used for a headlight, etc. of an automobile. In order to secure a space of an engine room when a high luminance discharge lamp is used for the head light of the automobile, a thickness of the discharge lamp in a depth direction from a socket is desired to be as thin as possible.
However, in a general high luminance discharge lamp, an igniter is connected to the socket of the discharge lamp, but this igniter needs a transformer which has a relatively large volume. Therefore, there is a problem that a lighting unit including the socket and the igniter becomes thick.
Therefore, as shown in Japanese Patent Application Laid-Open Publication No. 2004-206974 (Patent Document 1), it is considered that a drawing direction of a wiring for a drive wire is directed to a direction of a socket engaging surface so as to thin the lighting unit.
However, since a discharge bulb exists in the drawing direction of the drive wire if thus constructed, it is necessary to bend largely the drawn drive wire, and there are problems in view of workability and durability. When a normally used transformer is used as the igniter, there is possibility that a creeping discharge and a corona discharge occurs at a secondary side winding by a voltage generated in this winding, and a power supplied to the discharge bulb is limited. Therefore, there are problems that a high voltage cannot be applied to the discharge lamp and start of lighting the discharge lamp cannot be easily and speedily performed.